格尔木地区沙尘气溶胶硝酸盐含量及来源

沙尘气溶胶中硝酸盐的含量和来源对于全球氮排放估算具有重要意义。为了探讨格尔木沙尘气溶胶中硝酸盐的含量和来源,我们在格尔木2008年沙尘过程多发期1-6月进行了连续观测,并对收集的沙尘气溶胶样品进行了详细的水溶性离子色谱分析。结果显示:沙尘天气的大气总悬浮颗粒物(TSP)平均浓度及NO₃^-平均浓度分别为2 015.94 μg·m^-3和1.8 μg·m^-3,非沙尘天气两者平均浓度分别为274.68 μg·m^-3和0.74 μg·m^-3。观测期间,格尔木NO₃^-浓度和TSP浓度存在明显的季节变化,NO₃^-和TSP浓度变化均为春季>夏季>冬季。TSP与NO₃^-浓度的相关系数为0.67,春季两者相关系数为0.71,且Ca²⁺与NO₃^-浓度显著相关,推测格尔木沙尘气溶胶中NO₃^-离子可能主要来源于干旱区的地表物质。非沙尘天气期间NO₃^-/TSP浓度比值高于沙尘天气,且分布较为分散,表明非沙尘天气NO₃^-浓度受到人为源或气象条件的影响。

The Concentrations and Sources of Nitrate in Aerosol over Golmud,Qinghai, China

The study of particulate nitrate in the ambient air in continental area is of great importance to estimate the global nitrogen emission. To investigate the concentrations and sources of particulate nitrate in aerosol in the northern Tibetan Plateau, the water soluble(WS)nitrates were analyzed by ion chromatography for total suspended particulate(TSP)collected in Golmud from January to June, 2008. The average concentrations of TSP and the WS NO₃^- are 2 015.94 μg·m^-3 and 1.8 μg·m^-3 under dust condition, with 274.68 μg·m^-3 and 0.74 μg·m^-3 under non-dust condition, respectively. The concentrations of TSP and the WS NO₃^- show distinctive seasonal variations with a trend of spring>summer>winter. The correlation of the WS NO₃^- and TSP are quite obvious with a coefficient of r=0.67 for all samples and r=0.71 for the samples of spring in 2008. And the concentrations of NO₃^- have significant correlation with Ca²⁺. Thus we infer that the dust processes have mainly effects on the concentrations of the WS NO₃^-, and the surface soil should be the main sources for particulate nitrate. The ratios of NO₃^-/TSP are higher in dust samples than that of in non-dust samples, and the ratioes are scattered in non-dust samples. It indicates that the WS NO₃^- may mainly be affected by anthropogenic sources and local weather in non-dust conditions in Goumud.